Work holder



Aug. 6, 1929. L. T. KNOWLES 1,723,356

WORK HOLDER Filed Feb. 29, 1928 Patented Aug. 6, 19.29.

LOUIS T. IZNOV-ILES, G13 MINNEAPOLIS, MINNESOTA.

VIQRK I Application tiled February This invention relates to a work holder for use on lalhes, drill presses, rises etc, for linoly centering work to be operated upon. Work sccurcd to a face plate or similar holder, to be operated upon in a lathe, drill press, or the like, is now commonly clamped on. the face of the plate and is roughly adjusted and centered by use oil. radially spaced concentric grooves formed in the face at the plat Such an adjli nient suliicient for rough work. When it becomes necessary, however, to operate on work which has al ready hecnpartially machii'icd, andou certain other types of work, a more accurate and line adjustuanit must be made of the work on the holder. i ccuracy up to 3 ml of an inch can lJO'iillllC by an experienced mechanicby use of the concentric grooves. In the finest kind of opcr: tious, the work iuustfbe adjusted to l/lOOOth of an inch accu- "acy. Accordingly after the work has been secured in place, as is above described, the work is tapped slightly by use of rubber hammers to center the same. It will some t-ii'nes take a. skilled mechanic a considerable length of time to accurately center work on a face plate by this method, due to the fact that the zaps of the rubber hainnuars ca ,7 be accurately rcgulatml, repeatedly carrying the work from one oil center position to a scroud oltccnter position.

ll. is the object of this invention to proride a novel and improved work holder, which can be used for quickly and easily zuljusting workto accln'alely center the same with the nicest and liucst accuracy.

To this end, the invention consists in the novel parts and conil'iinations oi partshcreinafl'cr defined in the claims and described in the following SlYGlill'lCtlllOil made in coniu-ction with the z,ic .:oinpanying drawings, wherein like reference characters refer to the same or similar parts throughout the various views, and, in which,

Figure l is a. front elevation ola work holder embodying the present invention certain of the parts being broken away and shown in section;

l ig. 2 a VlOW in side elevation of the work holder, certain of the parts being broken away and. shown in section;

Fig. 3 a view in rear elevation of the work holder, certain of the parts being broken away and other parts bein shown in OIL i V i i 1 N anon tale-2a up He: has l.

lhe face of the with the usual. radially spaced and concert.

EOLDER.

1928. Serial No. 257,938.

of Fl 3, as is indicated by the arrows, and illustrating a clamp securing a piece of work ilhist'ratcd in dotted lines to the face plate of the lmlder.

Referring: to the drawings, the present invention is illustrated as being embodied in a chuck, ii'icli'iding a chuck mount 5, a backing plate {5 and a face plate 7. The chuck mount 5 has the usual screw threaded opening thcrcth 'ough, and is of standard type, and is releasably securable to the rear side of the backing plate (5, in the cmivmtional man nor, by studs 8 and nuts 9 so that the mount may be removed from the backing plate and auothin' mount of different size substituted therefor. Preferably, both the backing plate (3 and the face plate 7 are circular in shape and are of the same dial'neter, the face plate 7 being; (Iii considerably greater lil'iickucss than the backing plate (5. The plate Ton its face is provided with two diamctrical grooves 10 set at right angles to each other, and the grooves are of such shape in cross section but suitable work holding clamps ll may be mounted therein, to hold a piece of work such. as the work A on tile face plate. plate will also be provided tric grooves 12 for determining the proper positioninn of the work on the plate relative to the axial center thereof.

The rear side of the face plate 7 will abut the forward side of the backi g plate 6, so

that the face plate may be slit on the backing plate in a plane substantially parallel to the general plane of the backing plate, and at right angles to the axial centers of the chuck mount 5 and the two 'g ilalcs. l our substantially rectangular shaped recesses 13 are provided in the face plate 7. ccsses extend forwardly from the rear side of the face plate and project radially from the circuinferential edge of the plate inwardly to approximately half the distance between the edge of the plate and the center thereof, terminating in straight shoulders let at their inner ends. The recesses will be disposed at right angles to each other, so that the shoulders 1+1; of opposite recesses will be diametrically opposed in respect to the center of the face plate. Shoulders 1-1, as illustrated, will be set at right angles to each other to form portions of the sides of a square having its center in the axial center of t lace plate It will bc iiinlerstood, hu that th H 'l Ll-TlflPl it 1 he so arranged that they would form portions of the sides of a rectangle of any size. Four rectangular blocks of narrower width than the wit th of the recesses 13 formed integral with, or secured to, the forward side of the backing plate 6. These blocks are preferably spaced inwardly a short distance from the circumferential edge of the backing plate and are comparatively short in length relative to the length of the recesses 13. 'l he blocks 15 are radially arranged respective to the axis of the backing plate and are set at right angles to each other, so that opposite blocks will be diametrically opposed to each other. Each block has a screw threaded opening therethrough within which a screw 16 is situated, and the axes oi tie tour screws will be so arranged that they will be radial to the center of the backing plate and respectively set at right angles to one another. Each screw 16 has a broad, that faced circular head 17 at its inner end and has polygonal shaped key engaging portion 18 at its outer end. Small rectangular bearing blocks 19 are placed within the recesses 13 to abut the shoulders 14 and to extend bet-ween the sides of the recesses, and the heads 17 of the screws 16 bear against these bearing blocks.

. A number of comparatively large open ings 20 will be provided through the back ing plate 6, and these openings will be prel erably regularly arrangedin respect to the circumference of the backing plate. As illustrated in the drawings, two openings 20 are provided between each pair of blocks Secured in the rear side of the face plate 7 between adjacent recesses 18 therein, are studs 21 which extend rearwardly from the face plate through the openings 20 in the backing plate. The studs are of considerably smaller diameter than the diameter of the openings 20 and carry at the rear side of the facing plate, washers 22. These washers have openings therethrough slightly larger in diameter than the diameter of the studs for a purpose to be hereinafter described. Lock nuts 23 are threaded on the rear ends of the studs 21 and clamp against the washers 23. The washers are of such size as to fit completely over the rear ends of the openings 20, no matter what the position of the studs may be respect to the centers of the openings 20. The lock nuts 23 have slots 2% cut through one side oi the same at one of the corners thereof. Before the nuts are threaded on to the studs 23, they will be pounded slightly to reduce the spacing of the slots 23, whereupon as the nuts are threaded on to the studs, they will tightly fit thereon and can only be turned as the ends adjacent the openings 2e are sprung apart slightly. Thus, when the nuts are screwed down on the washers 22, they will hold their positions.

In assemblin the device, a film of oil will the facing and backing plates. Oil will also be supplied to the screws 16. The nuts 23 will be screwed down quite tightly on to washers 22. However, the nuts will not be screwed down so tightly that the washers cannot move in respect to the studs 21. As the openings through the wasaers 22 will be slightly larger diameter than the diameter of the studs 21, the relative tensi n exerted against the washers by the vari us nuts can b tested by the ease with which the washers 2 from the studs 21. By

2 will slide to and thus testing the various washers, the tension exerted by all the nuts can be made the same. The face plate 7 may, accordinglv, slide with equal freedom on the backing plate 6 in any direction. U

. ll hen it becomes desirable to =n ter piece oi work, such as the well A the chuck, the work will be clamped in pl co in the grooves 10 on the face of i as by the clamp 11, or similar means, 'ie work may be roughly adjuster rchv tive to the axial center of the face plate in the usual n anner by use of the grooves 12. L ore the work is placed on tie "ace plate. screws 16 will have been opera ed to the circumferential of iiacc backing plates and to tightly bear 0 all four bearing plates 19 to clamp the face plzte in position on the backing plate. A fine adjustment oi" the work rela tive to the axial center of the backing plate may now be made. A i

who of the screws 16 will be slightly loosened, wher upon the screw 16 opposite the loosened screw mav be ci'irrespondingly tightened. This actioii will cause he whole lace pl to more along a C' metrical line running through the axial ce tor of "he backing plate, and in a plan parallel to the general plane of the backing plate and at rig it angles to the axial center of the backing plate. 'lhe heads 17 of the two unmoved screws will continue to bear against their two bearing plates 13) during this moving action, so as to prevent movement of the face plate in any other han a line diametl'cal to the eetcr bl the backing plate. The oil iihn in erposed etween the abutting surfaces of the tvo plates will prevent a jerky movement, as the plates are slid, so that the finest adjustment can be made of the work relative to the axial center of the backing plate by the said movement of two of the screws. The studs 21. nuts 23 and washers 2:2 will move with the face plate, the tension of the nuts 24 on the washers 22 being such that movement of one plate relative to another will not be prevented and yet being suiiicient to form an oil tight joint between the abutting sides of the plates, so that the film or oil provided cannot escape. In actual practice, one screw 18 will be loosened, while the other is tightened, so that at all times during the moving action the face plate will be positively held from any but the desired movement by the four screws. hen the face plate has been moved, as specified in the one direction, the other two dian'ietrically opposed screws which have hitherto remained untouchet'l may be respectively tightened and loosened to more the face plate in a line diametrically across the backing plate at direct right angles to the fist line of movement. It will thus be seen that the work 'arricd on the face plate may be ad j usted by the four screws, to move the work along the lines of a right angle to any desired position relative to the axial. center of the bacl-zing plate. As all four of the screws bear directly against the hearing plates 19 and as the face plate may be moved without any jerky movement whatsoever, due t the oil film which may be provided between the abutting sides of the two plates, it'will be seen that the finest adjustment and eontcring of the work A may be oc'asioneifl. The inventorlias used the work holder in actual practice and has found that he can adjust work to 1 lOOOth of an inch accuracy, relative to the axial center of the backing plate within a few minutes.

Due to the fact that the heats 17 of the screws 16 are quite large, and also tothe fact that the sl'ioulders 14 are provided approximately midway between the center of the face plate and the circun'iferential edge thereof, no binding action will take place between the heads of diametrically opposed screws and their hearing blocks 19, asthe other screws are moved, Also, due to the fact that the shoulders 14L are spaced approximately midway between the center of the face plate and circumferential edge thereof, a long lever arm will be nrovided between the center of the backing plate and the shoulders 1"1: so that the screws will socurely hold the facing plate in position,

when the whole work holder is turned rapidly as on a lathe.

It will be understood that the screws 16 will be used for only fine adjustment of the work and, accordingly, there will be sufficient clearance between the sides of the openings 20 through the backing plate and the studs ill to secure the line adjustment. Also, the fine adjustment obtained by use of the screws will be insul'licient to throw the facing plate 7 oil center from the'backing plate stilliciently to interfere with the turning action of the chuck, as it is used on a lathe or similar rotating machine.

The blocks 15 and the recesses 13 may, of course, be reversed on the facing and backing plates without changing the operation of the device. Other means besides the grooves 10 and grooves 12 may be provided mounted on said backing plate, means on the face of said face plate for permitting work to be secured thereto and to be roughly centiered thereon, four screws mounted on said backing plate disposed radially in respect to the axial center of said backing plate and set at angles to each other, and four bearing portions on said face plateagainst each of which one of said screws is adapted to bear, said bearing portions forming portions of, the sides of a rectangle, whereby said face plate can be moved along two lines extending diametrically at right angles through the axial center of said backing plate, by adjustment of said. screws, and

said screws during and after such movement to finely adjust work carried on said face plate relative to the axial center of said backing plate.

2. A line centering work holder comprising, a backing plate, a face plate mounted on said backing plate for sliding movement inrespect thereto, means on the face of said face plate permitting work to be secured thereto and to be roughly adjusted thereon, comparatively narrow blocks mounted on said backing plate and projecting into comparatively wide recesses formed in said face plate, said recesses being radially arrangn-d in said face plate and having inner bearing ends forming portions of the sides of a true rectangle, screws mounted in said blocks and each. luivingan inner end bearing against one of the bearing portions of said recesses, said screws being radial to the axial center of said backing plate and being set at right angles to each oth r, whereby by adjustment of said screws, said face plate may he slid in a plane parallel to said face plate to a desired position to finely adjust work carried on the face plate relative to the axial center of said backing plate, and during and after such adjustment said face plate may be positively held in position by means of said screws.

A line centering work holder comprising, a backing plate having a series of large openings projecting therethrough, a face plate having its rear side bearing against said backing plate and slidable thereon,

I studs secured to said face plate and project-' ing rearwardly through said large openings but being of less diameter than the oliameter of sa1d openings to permit inoveid face plate may be positively held by ment of said face plate relative to said backing plate, washers surrounding said studs at the rear of said backing plate, lock nuts threaded onto said studs and bearing against the rear sides of said washers, said nuts be ing so adjusted as to hold said face plate and said backing plate together to form an oil tight joint between the opposing surfaces thereof, but yet permitting limited sliding m0 ement of said face plate relative to said backing plate, means on the face of said face plate for permitting work to be secured thereto and to be roughly centered thereon, and means for positively holding and sliding said face plate on said backing plate in any desired direction in a plane parallel to said backing plate to finely adjust work carried on said face plate relative to the axial center of said backing plate.

4t. The structure defined in claim 3, the openings through said washers being of slightly greater diameter than the diameter of said studs to permit slight movement of said washers relative to said studs to deter mine the relative tension between said nuts and said backing plate.

A fine centering work holder comprising, a backing plate, a face plate mounted on said hacking plate and having four recesses formed on the rear side thereof set at right angles to each other and radially disposed in respect to the center of said face plate, said face plate having bearing shoulders at the inner ends of said recesses set at right angles to each other, four blocks mounted on the forward side of said backing plate, radially disposed in respect to the center of said backing plate, set at right angles to each other and being of narrower width than the width of said recesses and fitting into said recesses, diametrically opposed screws mounted for movementiin opposite blocks and having heads hearing againstsaid shoulders in said face plate, and means for securing said face plate to said backing plate to permit a limited sliding movement of said face plate respective to the said back ing plate and in a plane parallel to the plane of said backing plate, whereby woriz carried by said face plate can be finely adjusted relative to the center of said backing plate and said face plate can be positively held during and after the adjustment thereof.

6. The structure defined in claim 5, the shoulders on said face plate being approxin'iately intermediately spa ed between the center of said plate and the edge. thereof.

The structure defined in claim 5, and bea ing plates disposed between the heads of screws and tile shoulders on said face h structure defined in claim 5, the heads 0 said screws having large bearing surfaces disposed at right angles to ra'lii projecting from the center of said face plate through the axial centers of said screws.

9. A fine centering work holder comprising, a backing plate, a face plate mounted on said backing plate for sliding movement thereon, means for permitting the work to be secured on the face of said face plate and to be roughly centered thereon, means for positively holding and at the same time sliding said face plate to an exact, desired, adjusted position on said backing plate by movement along two straight lines running diametrically through said backing plate and set at right angles to each other, and means preventing the movement of said face plate in all directions except along said two lines.

10. A work holder comprising a pair of plates slidably mounted on each other, four screws mounted on one of said plates and disposed radially in respect to the axial center of said plate and set at 90 angles to each other, four plane surfaced bearing portions on the other of said plates against each of which one of said screws is adapted to bear, said bearing portions forming sides of a rectangle, whereby one of said plates can be moved on the other plate along two lines extending dian'ietrically at right angle to each other through the center of the other plate by adjustment of said screws, and said movable plate can be positively held by said screws during and after such movement to finely adjust work carried on one of said plates relative to the axial center of the other plate.

In testimony whereof I atlix my signature.

LOUIS T. KnowLns. 

